Ergogenic effects of the combination of caffeine and New Zealand blackcurrant supplements on time trial

Abstract

The use of single supplements to enhance performance is widespread among athletes. The aim of this study was to increase knowledge about the combined effects of caffeine and New Zealand blackcurrant (NZBC) dietary supplements. In this counterbalanced alternating treatment single-case design, two participants each underwent four phases of four sessions in a double-blind, randomized order. After a 3-week pre-test phase, the supplement combinations of placebo/placebo, caffeine/placebo (5 mg/kg), NZBC/placebo (600 mg), and caffeine/NZBC (5 mg/kg + 600 mg) were taken and weekly performance tests were conducted to examine their effects on relative power (W/kg) during a 20-minute time trial on a bicycle. Data were analyzed descriptively and using the Tau-U calculator from Single Case Research. The ergogenic effect of caffeine was confirmed in both participants, with increases of 3.3% and 6.5%, while the positive effect of NZBC on performance was only seen in one participant (13.4%). The combination of caffeine and NZBC again increased performance in both participants (2.2% and 19.2%), but the data only showed a near additive effect of the supplements in one participant. The participants did not show a consistent performance improvement with the combined intake of the supplements caffeine and NZBC. Further studies are required to confirm or refute this evidence of the synergistic effects of these supplements.